Final answer:
Scientists use direct and indirect evidence to document the evidence of global warming, including temperature measurements and analysis of proxies like ice cores and tree rings.
Step-by-step explanation:
Scientists use a variety of tools to document evidence of global warming. Direct evidence for global warming comes from measurements of global land and ocean temperatures, which show an overall warming trend since the late 1800s. Indirect evidence for global warming comes from observations of its effects, such as the shrinking of glaciers and the analysis of proxies like ice cores, tree rings, and sediment cores that reveal past climate changes. By analyzing historical data, scientists can build a picture of Earth's changing climate over time.